Many absorbent articles, especially those designed and configured to absorb vaginal and/or urethral discharge, utilize pressure sensitive positioning adhesive on a backsheet layer to attach the article to a user's undergarment. To protect the positioning adhesive prior to use, a releasable sheet is typically applied over the adhesive. Disadvantages accompanying the use of a release sheet and positioning adhesive are numerous; some of which are illustrated below.
Release sheets are typically constructed from silicone coated paper, accounting for an expensive component in an absorbent article's composition. Moreover, consumers find it inconvenient and indiscreet to dispose of the sheet after removing it from the article.
One approach proposed for eliminating the need for a separate release sheet is to apply a release coating to a film overwrapper and adhere the article directly to the overwrapper. This approach eliminates some of the cost of a release sheet, but maintains the most expensive component, the coating itself. Another disadvantage of this approach is the requirement of an overwrapper. Many commercially available absorbent articles are sold in cartons or bags, and are thus not individually packaged with overwrappers.
U.S. Pat. No. 5,217,448 discloses an absorbent product having optional side panel usage. The products have side flaps with adhesive thereon and corresponding release areas on the undergarment-facing side of the product for the flaps to releasably adhere to. This configuration eliminates the need for a release sheet to protect the flap adhesive. The flaps can optionally be removed from the release area and attached to a user's undergarment. Additional zones of pressure sensitive adhesive occupy the undergarment-facing side of the article for maintaining the product's position during use, especially when the flaps are not employed. However, zones of positioning adhesive present other disadvantages. Portions of the positioning adhesive may remain in a user's undergarment after removing the absorbent article, creating the potential for the remaining adhesive to come into contact with the user's skin or permanently discolor her undergarment. Alternatively, the article may delaminate or tear upon removal if the adhesive has a bond strength to the undergarment greater than the integrity of the article itself. This presents difficult or unsanitary removal and disposal issues of the portions left in the undergarment.
Positioning adhesive can also exacerbate a common consumer complaint referred to as “bunching,” which renders absorbent articles uncomfortable and vulnerable to increased probability of peripheral leakage. The forces created between the article and the user's adjacent body parts create this phenomenon. During the dynamics of bunching, the positioning adhesive can adhere to itself creating a permanent crease or fold.
To eliminate positioning adhesives and release sheets altogether, absorbent articles have been designed having high coefficient of friction backsheets. U.S. Pat. No. 5,011,480 discloses such an article. A high coefficient of friction backsheet is a useful means for maintaining the article's position in the user's undergarment when the undergarment is next to the body, which applies a normal force to the article. When the user's undergarment is away from her body, little to no normal forces are exerted on the article, and the frictional characteristics of the backsheet provide minimal resistance to movement of the article. This allows the article to become shifted or separated from the undergarment when the user urinates or initiates usage of the article for the first time. Shifting can create comfort problems and positioning that is less than optimal for absorbing exudates. Separation may also result in article contamination, requiring the user to discard the article.